package com.cw.gui;

import java.awt.KeyEventPostProcessor;
import java.awt.Window;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JRootPane;
import javax.swing.MenuElement;
import javax.swing.MenuSelectionManager;
import javax.swing.SwingUtilities;
import javax.swing.plaf.basic.ComboPopup;

public class AltProcessor implements KeyEventPostProcessor {
    static boolean altKeyPressed = false;
    static boolean menuCanceledOnPress = false;
    static JRootPane root = null;
    static Window winAncestor = null;

    void altPressed(KeyEvent ev) {
        MenuSelectionManager msm =
            MenuSelectionManager.defaultManager();
        MenuElement[] path = msm.getSelectedPath();
        if (path.length > 0 && ! (path[0] instanceof ComboPopup)) {
            msm.clearSelectedPath();
            menuCanceledOnPress = true;
            ev.consume();
        } else if(path.length > 0) { // We are in ComboBox
            menuCanceledOnPress = false;
            ev.consume();
        } else {
            menuCanceledOnPress = false;
            JMenuBar mbar = root != null ? root.getJMenuBar() : null;
            if(mbar == null && winAncestor instanceof JFrame) {
                mbar = ((JFrame)winAncestor).getJMenuBar();
            }
            JMenu menu = mbar != null ? mbar.getMenu(0) : null;
            if(menu != null) {
                ev.consume();
            }
        }
    }

    void altReleased(KeyEvent ev) {
        if (menuCanceledOnPress) {
            return;
        }

        MenuSelectionManager msm =
            MenuSelectionManager.defaultManager();
        if (msm.getSelectedPath().length == 0) {
            // if no menu is active, we try activating the menubar

            JMenuBar mbar = root != null ? root.getJMenuBar() : null;
            if(mbar == null && winAncestor instanceof JFrame) {
                mbar = ((JFrame)winAncestor).getJMenuBar();
            }
            JMenu menu = mbar != null ? mbar.getMenu(0) : null;

            if (menu != null) {
                MenuElement[] path = new MenuElement[2];
                path[0] = mbar;
                path[1] = menu;
                msm.setSelectedPath(path);
            }
        } 
    }

    public boolean postProcessKeyEvent(KeyEvent ev) {
        if(ev.isConsumed()) {
            // do not manage consumed event
            return false;
        }
        if (ev.getKeyCode() == KeyEvent.VK_ALT) {
            root = SwingUtilities.getRootPane(ev.getComponent());
            winAncestor = (root == null ? null : 
                    SwingUtilities.getWindowAncestor(root));

            if (ev.getID() == KeyEvent.KEY_PRESSED) {
                if (!altKeyPressed) {
                    altPressed(ev);
                }
                altKeyPressed = true;
                return true;
            } else if (ev.getID() == KeyEvent.KEY_RELEASED) {
                if (altKeyPressed) {
                    altReleased(ev);
                } 
                altKeyPressed = false;
            }
            root = null;
            winAncestor = null;
        } else {
            altKeyPressed = false;
        }
        return false;
    }
}